Abstract
In field conditions, seven fertilization treatments were applied by randomized design with three replications. At a late growth stage of Chinese cabbage, the plant leaf chlorophyll content, photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) significantly increased upon the three fertilization modes, which were synthetic and organic fertilizers combined (SOF), synthetic fertilizer and dicyandiamide combined (SFD), and organic fertilizer inoculated live earthworms (OFE) than the other treatments. Organic fertilizer application significantly improved superoxide dismutase (SOD), Peroxidase (POD) and Catalase (CAT) activities and decreased malondialdehyde (MDA) accumulation, especially in the organic fertilizer inoculated live earthworms treatment. The SOF, SFD and OFE treatments improved the plant yield by 40.5%, 38.0% and 36.1% than the synthetic fertilizer applied alone treatment (SFB) and by 23.4%, 21.1% and 19.6% than the synthetic fertilizer in a split application treatment (SFT). Compared to single applied synthetic fertilizer, the OFE treatment significantly reduced nitrate content, and also improved sugar-acid ratio and soluble sugar and Vc content in the heads of the plant at the harvest stage. All this suggests the OFE treatment is a healthy, sustainable and environmentally friendly fertilization way for the Chinese cabbage production in north of China.
ACKNOWLEDGMENTS
The authors thank Dr. H. Y. Yang, University Hohenheim, Germany, for his critical reading and revision of the manuscript. Special acknowledgements are given to the editors and reviewers. This work was supported by the Projects in the National Science & Technology Pillar Program during the Twelfth Five-Year Plan Period (No. 2011BAD11B01; 2011BAD11B02), and the Shandong Agricultural University Postdoctoral Science Foundation funded project (No. 76226). The chemical fertilizer used in this experiment was provided by Shandong Kingenta Ecological Engineering Co., Ltd.